Closed github-learning-lab[bot] closed 2 years ago
ntoh*
macros5_macro_definitions.ql
ntohs
, ntohl
or ntohll
. Use the auto-completion in the Visual Studio Code extension to guide you:
from
to get a list of available classes in the CodeQL standard library for C/C++. Which class in this list represents macros? Create a variable with this class as its type.where
section, type <your_variable_name>
followed by a dot .
, and wait a moment to get the list of predicates available for a value in the variable's type. Hover over each predicate to see the inline documentation.or
keyword to combine multiple conditions where you want at least one condition to be met. Here we are interested in three possible macro names.or
you have 2 choices:
string::regexpMatch
in the built-in predicates for string. CodeQL uses the java.util.Pattern
regexp conventions.<your_variable_name>
to a list of choices <your_variable_name> in ["bar", "baz", "quux"]
Congratulations, looks like the query you introduced in ea48dbe3f8f2ccfec0f4990d05e17d4258042afa finds the correct results!
If you created a pull request, merge it.
Let's continue to the next step.
Step 5: Using different classes and their predicates
We want to identify integer values that are supplied from network data. A good way to spot those is to look for use of network ordering conversion macros such as
ntohl
,ntohll
, andntohs
.In the
from
section of the query, you declare some variables, and state the types of those variables. The type tells us what the possible values are for the variable.In the previous query you were querying for values in the class
Function
to find functions in the source code. We have to query a different type to find macros in the source code instead. Can you guess its name?NOTE: These Network ordering conversion utilities can be macros or functions depending on the platform. In this course, we are looking at a Linux database, where they are macros.